Adding trace from apache error log:

[Tue Mar 05 06:25:21 2013] [error] \x1b[31;1mUnauthorized: Unauthorized (HTTP 401)\x1b[0m
[Tue Mar 05 06:25:21 2013] [error] Traceback (most recent call last):
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/usage/base.py", line 112, in get_quotas
[Tue Mar 05 06:25:21 2013] [error]     self.quotas = quotas.tenant_quota_usages(self.request)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/horizon/utils/memoized.py", line 33, in __call__
[Tue Mar 05 06:25:21 2013] [error]     value = self.func(*args)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/usage/quotas.py", line 84, in tenant_quota_usages
[Tue Mar 05 06:25:21 2013] [error]     for quota in get_tenant_quota_data(request, disabled_quotas):
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/usage/quotas.py", line 73, in get_tenant_quota_data
[Tue Mar 05 06:25:21 2013] [error]     return _get_quota_data(request, "tenant_quota_get", disabled_quotas)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/usage/quotas.py", line 61, in _get_quota_data
[Tue Mar 05 06:25:21 2013] [error]     quotasets.append(getattr(cinder, method_name)(request, tenant_id))
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/share/openstack-dashboard/openstack_dashboard/wsgi/../../openstack_dashboard/api/cinder.py", line 125, in tenant_quota_get
[Tue Mar 05 06:25:21 2013] [error]     return QuotaSet(c_client.quotas.get(tenant_id))
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/v1/quotas.py", line 37, in get
[Tue Mar 05 06:25:21 2013] [error]     return self._get("/os-quota-sets/%s" % (tenant_id), "quota_set")
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/base.py", line 141, in _get
[Tue Mar 05 06:25:21 2013] [error]     resp, body = self.api.client.get(url)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/client.py", line 185, in get
[Tue Mar 05 06:25:21 2013] [error]     return self._cs_request(url, 'GET', **kwargs)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/client.py", line 147, in _cs_request
[Tue Mar 05 06:25:21 2013] [error]     self.authenticate()
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/client.py", line 293, in authenticate
[Tue Mar 05 06:25:21 2013] [error]     auth_url = self._v1_auth(auth_url)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/client.py", line 311, in _v1_auth
[Tue Mar 05 06:25:21 2013] [error]     resp, body = self.request(url, 'GET', headers=headers)
[Tue Mar 05 06:25:21 2013] [error]   File "/usr/lib/python2.7/dist-packages/cinderclient/client.py", line 136, in request
[Tue Mar 05 06:25:21 2013] [error]     raise exceptions.from_response(resp, body)
[Tue Mar 05 06:25:21 2013] [error] Unauthorized: Unauthorized (HTTP 401)

Looks like its something to do with cinder. However I have not configured cinder yet due to this bug - https://bugs.launchpad.net/cinder/+bug/1144858.

Are the two related?